Novel power converter topologies to interface solar power to power grid with battery backup

The main aim of this thesis is to develop a solar energy system for domestic utilities, using a bi-directional DC-DC boost converter with a battery storage system in it. Topologies of the converters employed in the existing system are not efficient, especially in high power applications because of complicated structures with many power devices. In order to step up the DC voltage of the solar panel to a value suitable for AC power conversion, the DC-DC converter topologies has used either multiple stages of voltage amplification or complicated structures with many power devices as the voltage gain offered by the standard boost converter is not adequate enough. This has led to the use of complicated switching control methods. As a result of such power converters with low power density, the cost of the system is also high with relatively low efficiency. The above-mentioned shortcomings have led researchers to investigate new topologies of converters and efficient control methods. The thesis investigates the existing topologies of DC-DC boost converters pointing out advantages and disadvantages and presents ten new topologies that are superior to existing ones. Detailed analysis of converters is presented, and the mathematical model is developed to determine the voltage gain as a function of duty cycle. The presented converter topologies are also designed, and prototypes fabricated in the laboratory. The fabricated converters are tested experimentally using Arduino micro-controller. Programs are developed to control the converters in different modes of operation and the performance curves are generated. The experimental results support the theoretical model developed and the obtained results are presented in the thesis. A bi-directional DC-AC converter topology is also developed to interface the solar panel to the AC grid. The developed topology makes use of one of the DC-DC converter topologies presented and offers battery backup facility in it. This system can be controlled to store power either from AC grid or from the solar panel and can power the AC load or inject power to the grid. Appropriate control methods are developed for the bi-directional converter system and extensive simulation studies are conducted using MATLAB/Simulink to demonstrate the operation of the system in different modes of operation and simulation results are also presented. The converter system has also been fabricated and tested with solar panels. The test results of different modes of operation are also presented. Finally, the authors’ viewpoint in the development of power electronics in solar application is presented